Alexis Sanchez and Mesut Ozil helped Arsenal keep their Champions League hopes alive on Monday as the Gunners secured a 2-1 win against Middlesbrough at the Riverside Stadium.

Amid fan unrest over Arsene Wenger's future and the club's poor run of recent results, a much-changed Gunners side demonstrated desire and focus to seal all three points against a team desperate to avoid relegation.

Sanchez first fired in a superb free kick in the 42nd minute to bring the game into life after a slow start before Negredo volleyed in just after the break to hand hope to the hosts.

But Ozil's close-range effort in the 71st minute ensured Arsenal moved back into sixth place in the league standings, seven points behind fourth-placed Manchester City and with two games in hand over Pep Guardiola's side.

The humbling 3-0 defeat to Crystal Palace at Selhurst Park one week ago had clearly left a mark on Wenger, with the Frenchman opting to make a number of changes for the trip to the Riverside Stadium - and also a switch in formation.

For the first time since 1997, Wenger decided to field a three-man defence which comprised Laurent Koscielny, Gabriel and Rob Holding - who made his first league start since August.

With Petr Cech also returning from injury and Hector Bellerin dropping to the bench, Arsenal's starting team on Monday night looked very different to the one that crumbled in south London seven days ago.

And the changes appeared to take some time for the visitors to get used to, although Alex Oxlade-Chamberlain - playing in the right wing-back role - certainly handed Boro a lot of work to deal with early on with his forays forward.

Indeed, after getting an early booking for a foul on Fabio, many of Arsenal's best attacks came down Oxlade-Chamberlain's flank. And it was his corner kick that saw Daniel Ayala pull down Olivier Giroud in the area only for referee Anthony Taylor to deem the foul wasn't deserving of a spot-kick.

With Middlesbrough being let off the hook, the hosts responded by going on the counter and putting the ball into the back of Arsenal's net five minutes later - although it was ruled out for offside.

The move started from a free kick, which Giroud had given away, and ended in an offside Marten de Roon heading past Cech.

Arsenal upped their tempo and, after Boro gave away a free kick in a dangerous position just outside the area four minutes from time, Sanchez proved the difference with his superb effort.

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The Chile star superbly curled his set piece into the left-hand side of the goal to open the scoring for the visitors and net his 19th Premier League goal of the season.

If Arsenal thought, however, that Boro would prove easy to contain in the second period they were quickly proved wrong.

Just four minutes after the re-start, Sanchez gave the ball away cheaply which allowed Stewart Downing to launch a counter-attack and cross the ball in for Negredo.

Koscielny appeared to be unaware of the striker's position, and that allowed Negredo to superbly volley the ball into the net to restore parity.

The home side continued to push men forward and they could have had another when Downing's 54th minute effort flew over the bar before Ayala forced Cech into a last-ditch stop with his header.

Ozil then came close down the other end of the pitch but saw Brad Guzan clear Sanchez's ball from the German's path, although it wasn't long before Ozil did get on the scoresheet.

Sanchez was the instigator of the goal after he played it into the box where Aaron Ramsey was waiting. The midfielder controlled it with his chest and allowed it fall to Ozil, who coolly fired in from close range to hand Arsenal the lead once more.

Boro tested Arsenal's three-man defence several times as the game approached full-time but they held out to ensure the Gunners secured a hardfought 2-1 win.